X-ray backscatter imaging technique is one of primary technologies in a security inspection field, such as a human body and a vehicle. By X-ray scanning the human body and the vehicle, etc., backscattered signals of the X-ray are received by using a large-area ray detector, and through data collection and image processing, the backscattered images of a scattered object may be obtained.
In a backscatter security inspection technique, performance indications of the backscatter detector apparatus are directly related to an image quality and a detection rate of an object to be detected.
A detector structure having a large-area entrance window capable of receiving X-rays and a higher detection efficiency is a critical request of a detector for backscatter detection. In addition, a technical means of the backscatter imaging technique in a flying spot manner is used currently, which determines that the detector should use an integral mode, the X-ray signal may be converted to detectable electrical signals, and a conversion time should be as short as possible, generally within several microseconds.
At present, the common detectors that may be used for large-area ray detection include gas detectors, semiconductor detectors, and combined detectors formed by scintillators and various photomultipliers.
The gas detectors mainly include an ionization chamber, a proportional tube, and a G-M count tube which work in different amplification regions. Since Charpark invented a multi-wire proportional chamber and a micro-strip gas detector (MSGC), various proportional forms based on micro-strips, microfilaments, micro-pores and micro-webs and a lot of variant structures of the gas detectors come out. Because the position resolution and the counting rate of such gas detectors are greatly improved, they are readily used for scientific research. However, an incidence depth of the rays permitted by most of the gas detectors in a new form of a high position accuracy in the market is not enough, generally between a few millimeters and a few centimeters. When number and position of photons of the incident rays are correctly given, the total energy and dose of incident rays cannot accurately reflected. Most photons have limited energy deposition, and thereby having a lower detection efficiency. In addition, semiconductor detectors are widely used for ray detection, however, there still exits such problems that the detector has a smaller sensitive area and the environmental stability needs to be improved. In addition, the combined detector formed of a scintillator(s) and a photomultiplier(s) is used for the large-area ray detection, but its light collection conversion effect is lower and its cost is higher.
The above information disclosed in this BACKGROUND section is only for enhanced understanding of the background of the disclosure and therefore it may contain information that does not constitute the relevant technology known to those skilled in the art.